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WAEC Further Mathematics 2011 Question 39

Question 39

Vectors

Find the unit vector in the direction of −5i + 12j.

  1. A.1/13(−5i − 12j)
  2. B.1/13(5i + 12j)
  3. C.1/13(−5i + 12j)
  4. D.1/13(5i + 12j)
Show the answer and explanation

Answer: C (1/13(−5i + 12j))

Explanation

|−5i + 12j| = √(25 + 144) = 13, so the unit vector is (1/13)(−5i + 12j).